Bring a large pot of lightly salted water to a simmer. Add cauliflower and broccoli and simmer until just tender 5-6 minutes. Rinse with cold water to stop the cooking process. Allow to drain well, see note.
Meanwhile heat a large skillet over medium and add oil. When oil is hot add chicken thighs, searing and cooking 4-5 minutes per side until just cooked. Remove to a plate and set aside. To the same skillet add mushrooms and cook until browned and most of the moisture has evaporated, about 4 minutes. Add garlic and sauté for 1 minute.
In a large bowl whisk together mushroom soup, mayonnaise, curry powder, onion powder, pepper and lemon juice.
Cut cook chicken into large strips and add to mushroom soup mixture along with mushrooms, vegetables and 1 cup of the cheddar cheese. Stir gently to combine. Spread into a lightly greased casserole dish and sprinkle with remaining cheese. Bake for about 30 minutes until bubbling.
-I find rolling drained vegetables in a clean kitchen towel removes more moisture.
-A great low carb dinner option on its own, but also wonderful with rice, mashed potatoes, quinoa or crusty bread.